Cryosphere – Ocean

The science questions shown in the table above align closely with the Climate and Environmental Science Division’s (CESD) mission objectives to “advance a robust predictive understanding of Earth’s climate and environmental systems and to inform the development of sustainable solutions to the Nation’s energy and environmental challenges.”

Near-term and long-term experiments accompany the overarching question of each science driver. These experiments represent simulation targets for v1 and v2 of the E3SM system during the first 4 – 6 years of the project (Phase I and II) and for v3 and v4 in the 10-year horizon. The v1 and v2 simulation campaigns are designed to “stretch” goals for the initial round of E3SM development and preparatory steps toward a grand challenge objective suitable for the extreme-scale computing resources anticipated for 2020 and beyond. The v3/v4 campaign is designed to revolutionize the project’s projections connected with each driver and utilize the full power of the Exascale systems leveraged with transformative advances in model physics, numerical formulation, analytics, and computational implementation.

Consistent with the three science drivers and associated overarching science questions, the science questions motivating the near-term, medium-term, and long-term model development and experiments are listed in the table.

The v1 science questions investigate the impacts of ocean-ice interactions on melting of the Antarctic Ice Sheet (AIS). They motivated the development of key model features in E3SM v1, including coupling of ocean-ice processes in the Antarctic ice shelf.

In v2, the cryosphere question continues to investigate the AIS but the scope is broadened to understand the role of atmosphere, ocean, and sea ice in mediating melting of the ice sheet.

The ability to address the v2 questions would still be limited by model resolution as mesoscale convective systems that are responsible for 30-70% of warm season rainfall in the U.S. and ice melt processes at the margin of the AIS, among other multiscale processes, are not well simulated at the resolutions afforded in our v2 simulation campaign. Furthermore, the representations of some important processes would still be inadequate or missing in the v2 model. Hence in v3/v4, the science questions will build on and extend from the v1/v2 questions to address major uncertainties in predicting future changes in cryosphere systems. This motivates significant model development to address processes that are poorly represented or missing (e.g., subglacial hydrology) in v1/v2.

Progressing through four versions of E3SM, the science questions, summarized in the table, will be addressed by optimizing the use of higher resolution, increasing complexity, and larger ensemble size with the project’s exascale computational strategy to improve predictions of future changes in cryosphere systems that challenge energy production and use.